Field
The present disclosure generally relates to techniques for vertical optical coupling of optical signals. More specifically, the present disclosure relates to an integrated circuit that includes a metalized facet to facilitate vertical optical coupling of the optical signal.
Related Art
Silicon photonics is a promising technology that can provide large communication bandwidth, low latency and low power consumption for inter-chip and intra-chip optical interconnects or links. A key component for use in inter-chip and intra-chip optical interconnects is optical couplers that can be integrated into integrated circuits that include other optical components.
One type of optical coupler provides vertical optical coupling of optical signals perpendicular to a plane of an integrated circuit. Such surface-normal optical couplers can facilitate optical communication between adjacent photonic chips.
However, fabricating surface-normal optical couplers is often difficult. For example, it can be difficult to fabricate a negative facet having an angle of 45°. In particular, such facets typically cannot be fabricated using existing reactive-ion etching techniques, and have only been demonstrated using complicated fabrication tool modifications.
Similarly, while diffraction gratings are often used as optical couplers, it is usually not possible to obtain vertical optical coupling using a diffraction grating. In addition, diffraction gratings typically have back-reflections, which can have a negative impact on some optical devices (such as hybrid optical sources, e.g., hybrid lasers).
Furthermore, while vertical optical coupling can be achieved using an inverse taper to expand the optical mode of an optical signal, this approach typically can only be used at the edge of the photonic chip.
Consequently, existing approaches for providing vertical optical coupling on integrated circuits are often complicated and expensive, and usually do not scale well.
Hence, what is needed is an optical coupler that does not suffer from the above-described problems.